Fast Simulation Tool Research Articles

Dynamic response analysis of a multi-column tension-leg-type floating wind turbine under combined wind and wave loading

Floating wind turbines (FWTs) are subjected to combined aerodynamic and hydrodynamic loads varying both in time and amplitude. In this study, a multi-column tension-leg-type FWT (i.e., WindStar TLP system) is investigated for its global performance under normal operating conditions and when parked. The selected variables are analysed using a fully coupled aero-hydro-servo-elastic time domain simulation tool FAST. Three different loading scenarios (wind only, wave only and both combined) are examined to identify the dominant load influencing each response. The key response variables are obtained and compared with those for an NREL 5MW baseline wind turbine installed on land. The results should aid the detailed design of the WindStar TLP system.

F ault S im

As memory systems scale, maintaining their Reliability Availability and Serviceability (RAS) is becoming more complex. To make matters worse, recent studies of DRAM failures in data centers and supercomputer environments have highlighted that large-granularity failures are common in DRAM chips. Furthermore, the move toward 3D-stacked memories can make the system vulnerable to newer failure modes, such as those occurring from faults in Through-Silicon Vias (TSVs). To architect future systems and to use emerging technology, system designers will need to employ strong error correction and repair techniques. Unfortunately, evaluating the relative effectiveness of these reliability mechanisms is often difficult and is traditionally done with analytical models, which are both error prone and time-consuming to develop. To this end, this article proposes F ault S im , a fast configurable memory-reliability simulation tool for 2D and 3D-stacked memory systems. FaultSim employs Monte Carlo simulations, which are driven by real-world failure statistics. We discuss the novel algorithms and data structures used in FaultSim to accelerate the evaluation of different resilience schemes. We implement BCH-1 (SECDED) and ChipKill codes using FaultSim and validate against an analytical model. FaultSim implements BCH-1 and ChipKill codes with a deviation of only 0.032% and 8.41% from the analytical model. FaultSim can simulate 1 million Monte Carlo trials (each for a period of 7 years) of BCH-1 and ChipKill codes in only 34 seconds and 33 seconds, respectively.

A fast method for optical simulation of flood maps of light-sharing detector modules

Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. We present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We simulated conventional block detector designs with different slotted light guide patterns using the new approach and compared the outcomes with those from GATE simulations. While the two approaches generated comparable flood maps, the new approach was more than 200–600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials.

FAST Simulation Tool Containing Methods for Predicting the Dynamic Response of Wind Turbines

FAST Simulation Tool Containing Methods for Predicting the Dynamic Response of Wind Turbines

ShadingPlus—a fast simulation tool for building shading analysis

Shading system plays a significant role in reducing building energy demand. To analyse the performance of a shading system, traditional method is either conducting experimental tests for solar heat gain coefficient (SHGC) or through detailed energy simulation for energy saving during specific period. But no simulation tool is able to accomplish the two objectives at the same time, and the latter is always too detailed and cumbersome with traditional simulation tools. To help architects analyse the shading system in a more comprehensive and simple way, a fast simulation programme—ShadingPlus—is proposed and developed in this work. With EnergyPlus as its core simulation engine, ShadingPlus applies an optimal methodology to calculate SHGC. Moreover, annual energy saving calculation is also available with ShadingPlus which reflects shading system in a more realistic way. It is expected that the analysis for shading system can be greatly simplified using this tool. Case studies are also given to illustrate the way ShadingPlus works.

Planning for sustainable development of energy infrastructure: fast – fast simulation tool

Energy management has significant impact on planning within local or regional scale. The consequences of the implementation of large-scale renewable energy source involves multifaceted analyses, evaluation of environmental impacts, and the assessment of the scale of limitations or exclusions imposed on potential urbanized structures and arable land. The process of site designation has to acknowledge environmental transformations by inclusion of several key issues, e.g. emissions, hazards for nature and/or inhabitants of urbanized zones, to name the most significant. The parameters of potential devel opment of energy-related infrastructure of facility acquire its local properties – the generic development data require adjustment, which is site specific or area specific. FAST (Fast Simulation Tool) is a simple IT tool aimed at supporting sustainable planning on local or regional level in reference to regional or district scale energy management (among other issues). In its current stage, it is utilized – as a work in progress – in the assessment of wind farm structures located within the area of Poznan agglomeration. This paper discusses the implementation of FAST and its application in two conflicting areas around

Low-cost simulation of guided wave propagation in notched plate-like structures

The paper deals with the development of low-cost tools for fast computer simulation of guided wave propagation and diffraction in plate-like structures of variable thickness. It is focused on notched surface irregularities, which are the basic model for corrosion damages. Their detection and identification by means of active ultrasonic structural health monitoring technologies assumes the use of guided waves generated and sensed by piezoelectric wafer active sensors as well as the use of laser Doppler vibrometry for surface wave scanning and visualization. To create a theoretical basis for these technologies, analytically based computer models of various complexity have been developed. The simplest models based on the Euler–Bernoulli beam and Kirchhoff plate equations have exhibited a sufficiently wide frequency range of reasonable coincidence with the results obtained within more complex integral equation based models. Being practically inexpensive, they allow one to carry out a fast parametric analysis revealing characteristic features of wave patterns that can be then made more exact using more complex models. In particular, the effect of resonance wave energy transmission through deep notches has been revealed within the plate model and then validated by the integral equation based calculations and experimental measurements.

An assessment of the sea breeze energy potential using small wind turbines in peri-urban coastal areas

From wind speed data recorded hourly at 2m high during 18 years (1993–2010) in the Llobregat Delta (15km south of Barcelona city; northeast of the Iberian Peninsula), wind speed distributions at 10m high were computed for the whole year and for the sea breeze period (from March 1 to September 30, from 10 to 19 local time). Weibull probability density functions fitted to the distributions were used to assess the wind energy generated by two off-grid small wind turbines: the IT-PE-100 and the HP-600W. Results from FAST and AeroDyn simulation tools were compared with those obtained by applying measured wind speeds to manufacturer power curves. Using manufacturer data, the IT-PE-100 would deliver 132kWh during the whole year (70kWh during the sea breeze period). From the simulations, the IT-PE-100 would deliver 155kWh during the whole year (80kWh during the sea breeze period). It is concluded that the sea-breeze is an interesting wind energy resource for micro-generation, not only in the Mediterranean basin but in other areas of the world with similar wind regimes, and particularly in peri-urban coastal areas where large-scale wind farms cannot be implemented.

Voltage Sources in 2D Fourier-Based Analytical Models of Electric Machines

The importance of extensive optimizations during the design of electric machines entails a need for fast and accurate simulation tools. For that reason, Fourier-based analytical models have gained a lot of popularity. The problem, however, is that these models typically require a current density as input. This is in contrast with the fact that the great majority of modern drive trains are powered with the help of a pulse-width modulated voltage-source inverter. To overcome that mismatch, this paper presents a coupling of classical Fourier-based models with the equation for the terminal voltage of an electric machine, a technique that is well known in finite-element modeling but has not yet been translated to Fourier-based analytical models. Both a very general discussion of the technique and a specific example are discussed. The presented work is validated with the help of a finite-element model. A very good accuracy is obtained.

Computational modeling and simulation of rupture of membranes and thin films

This paper presents a simple computational model for the rapid simulation of rupture on membranes and thin films. The proposed approach treats these surface structures as a collection of particles forming a discrete dynamical system, which is described by Newtonian equations in a purely mechanistic way. Detailed aspects about particle interactions are discussed and resolved. The main advantages of such an approach are that (1) it can offer a good picture of the dynamics of the rupture, yet resorting to only very simple descriptions of the underlying microstructure of the membrane or thin film, and (2) such different systems as structural fabrics, thin biological tissues and lipid membranes can be modeled under the same general framework. A time integration scheme is formulated for solution of the system dynamics, and examples of numerical simulations are provided. Computational particle-based models render reliable and fast simulation tools. We believe they can be very useful to study rupture phenomena on membranes and this films.

A separated representation of an error indicator for the mesh refinement process under the proper generalized decomposition framework

Today industries do not only require fast simulation techniques but also verification techniques for the simulations. The proper generalized decomposition (PGD) has been situated as a suitable tool for fast simulation for many physical phenomena. However, so far, verification tools for the PGD are under development. The PGD approximation error mainly comes from two different sources. The first one is related with the truncation of the PGD approximation and the second one is related with the discretization error of the underlying numerical technique. In this work we propose a fast error indicator technique based on recovery techniques, for the discretization error of the numerical technique used by the PGD technique, for refinement purposes.

Evaluation of a Thermosyphon Heat Pipe Operation and Application in a Waste Heat Recovery System

Efficient and economical utilization of industrial waste heat would result in reduced energy use and thereby contribute to reduction of greenhouse gas emissions to the atmosphere. Two-phase thermosyphon technology has demonstrated the potential capability for waste heat recovery, but it has not been yet utilized in large-scale industrial applications. As a part of an industrial project, various types of thermosyphon heat pipes have been designed and tested for extraction of waste heat and process control in aluminum industry. This article presents the heat and mass transfer model, developed to provide a fast and accurate simulation tool for industrial application of thermosyphon heat pipe technology for waste heat utilization. The mathematical model considers the energy, momentum, and mass transfer equations, in their one-dimensional form, to predict output parameters of the thermosyphon and enable parametric and sensitivity analysis. The mathematical model structure is set up in a way that the least numerical cost and time is spent while the model accuracy is kept at acceptable level for the defined application. To provide experimental data for validation of the simulation model, the proposed thermosyphon was tested experimentally using a test set-up instrumented for this purpose. The simulation results are found to be in good agreement with the experimental data. The developed model and code are viable to be used as a simple and fast tool for modeling, design, and optimization of the thermosyphon as an element in a heat recovery module.

Simulation tool coupling nonlinear electrophoresis and reaction kinetics for design and optimization of biosensors.

We present the development, formulation, validation, and demonstration of a fast, generic, and open source simulation tool, which integrates nonlinear electromigration with multispecies nonequilibrium kinetic reactions. The code is particularly useful for the design and optimization of new electrophoresis-based bioanlaytical assays, in which electrophoretic transport, separation, or focusing control analyte spatial concentration and subsequent reactions. By decoupling the kinetics solver from the electric field solver, we demonstrate an order of magnitude improvement in total simulation time for a series of 100 reaction simulations using a shared background electric field. The code can efficiently handle complex electrophoretic setups coupling sharp electric field gradients with bulk reactions, surface reactions, and competing reactions. For example, we demonstrate the use of the code for investigating accelerated reactions using isotachophoresis (ITP), revealing new regimes of operation which in turn enable significant improvement of the signal-to-noise ratio of ITP-based genotypic assays. The user can define arbitrary initial conditions and reaction rules, and we believe it will be a valuable tool for the design of novel bioanalytical assays. We will offer the code as open source, and it will be available for free download at http://microfluidics.technion.ac.il.

Optimizing Operation Rules of Sluices in River Networks Based on Knowledge-driven and Data-driven Mechanism

Many river networks are controlled by sluices, especially in plain area. To prevent potential floods, maintain water level, and improve water environment in the inner river, the water transfer of river networks is needed and executed often in terms of optimized operation rules of sluices planned in advancing. To guarantee maintaining the optimized operation status, the provision of appropriate operating framework of sluices in river networks is necessary and presented in this study based on the knowledge-driven and data-driven mechanism. The general framework is formed by River Networks Mathematical Model (RNMM), Artificial Neural Networks (ANN) and Genetic Algorithms (GA), in which, ANN is used to build a rapid simulation of the flow variables in river networks, RNMM is used to train the ANN model, and GA method, whose fitness function is constructed by the ANN model, is used to optimize the operation rules of sluices. As a demonstration, the framework was applied to water transfer project of the tidal river networks locating in Pudong New Area of Shanghai in mainland China. Firstly, RNMM of Pudong was built and validated according to observed data during water transfer tests. Then, the Backward Propagation Neural Networks (BPNN) model was established as the fast simulation tool of flow variables of river networks through the numerical experiments with RNMM. The Generalized Genetic Algorithms (GGA) was recommended as optimization algorithm of sluices operation rules. Through comparing the optimization results with the RNMM simulation outputs under eight cases, it is verified that the framework can offer sub-optimal operation rules of sluices in river networks and present excellent speediness, robustness and flexibility. It is encouraged to be applied to more complicated, practical problems.

A computational framework for simulation of the delivery of substances into cells.

In this paper, we propose a simple computational framework for the rapid simulation of the delivery of substances into cells. Our approach treats the substances and the cell membrane as a collection of particles forming a discrete dynamical system, which is described by Newtonian equations in a purely mechanistic way. Detailed aspects about the modeling of particle interactions are discussed and resolved. The main advantage of such an approach is that it can offer a good qualitative picture of the delivery mechanism without the need to resort to detailed descriptions of the complex intermolecular interactions that are observed at small scales of the cell membrane. A numerical time integration scheme is formulated for solution of the system dynamics, and examples of simulations are provided. Computational particle-based models render reliable and fast simulation tools. We believe they can be very useful to help advance the design of delivery systems.

A Performance Analysis Methodology for Multicore, Multithreaded Processors

A key challenge to program a chip multiprocessor (CMP) is how to evaluate the performance of various possible program-task-to-core mapping choices during the initial programming phase, when the executable program is yet to be developed. In this paper, we put forward a thread-level modeling methodology to meet this challenge. The idea is to model thread-level activities only and overlook the instruction-level and microarchitectural details, except those having significant impact on the thread-level performance. Moreover, since the thread-level modeling is much coarser than the instruction-level modeling, the analysis at this level turns out to be significantly faster than that at the instruction level. These features make the methodology particularly amenable for fast performance evaluation of a large number of program-task-to-core mapping choices during the initial programming phase. Based on this methodology, an analytic modeling technique based on queuing theory and a fast simulation tool are developed, both allowing for fast performance prediction of CMPs. Case studies based on a large number of code samples available in IXP1200/2400 workbenches demonstrate that the maximal sustainable line rates estimated using our simulation tool and queuing network models are consistently within 6 and 8 percent of cycle-accurate simulation results, respectively.

An Approximate Analytical Approach to Steady State Simulation of Unglazed Solar Collectors

This paper illustrates the thermal modeling of a flat plate unglazed solar collector with the aim of developing a simplified but accurate method for the collector steady state simulation without requiring a large amount of computational power and time. T he 1D+1D model is derived from the Riesz-Galerkin method applied to the approximate analytical solution of the heat equation. The model allows calculating heat transfer rate, fluid outlet temperature, collector efficiency and plate temperature distributio n. Accuracy and ability in simulating solar collector are checked using a 2D finite-difference model as a benchmark. The results of the simplified model show very good agreement with those provided by the finite-difference model, allowing to state that the simplified model is a valuable tool for fast and reliable collector simulation.

Analytical Modeling of Industrial-Related Silicon Solar Cells

Fast and accurate simulation tools are key to increasing our understanding of silicon-based solar cells. A lucid graphical unit interface and experimentally obtained input parameters help make these tools accessible for a wide range of users. In this paper, we present a fast Excel tool based on the well-known two-diode model supporting conventional and metal-wrap-through cell architectures. The selective emitter approach, spatial varying emitter recombination, and optical simulations are taken into account. A set of consistent input parameters, including the emitter recombination in the passivated case, as well as the metal contacted for both idealities, are given as a function of the emitter sheet resistance. This set on input parameters is associated with industrial-related technologies for conventional and metal-wrap-through silicon solar cells.

Una estrategia basada en la descomposición propia generalizada para aplicaciones gobernadas por datos dinámicos

Dynamic Data Driven Application Systems (DDDAS) appear as a new paradigm in the field of applied sciences and engineering, and in particular in simulation-based engineering sciences. By DDDAS we mean a set of techniques that allow the linkage of simulation tools with measurement devices for real-time control of systems and processes. DDDAS entails the ability to dynamically incorporate additional data into an executing application, and in reverse, the ability of an application to dynamically steer the measurement process. DDDAS needs for accurate and fast simulation tools making use if possible of off-line computations for limiting as possible the on-line computations. We could define efficient solvers by introducing all the sources of variability as extra-coordinates in order to solve off-line only once the model to obtain its most general solution to be then considered in on-line purposes. However, such models result defined in highly multidimensional spaces suffering the so-called curse of dimensionality. We proposed recently a technique, the Proper Generalized Decomposition (PGD), able to circumvent the redoubtable curse of dimensionality. The marriage of DDDAS concepts and tools and PGD off-line computations could open unimaginable possibilities in the field of dynamics data-driven application systems. In this work we explore some possibilities in the context of parameter estimation.

SCIROCCO+: Simulation Code of Interferometric-observations for ROtators and CirCumstellar Objects including Non-Radial Pulsations

The VLTI (Very Large Telescope Interferometer) makes available milli-arcsecond-scale observations in the infrared. It offers new possibilities for constraining stellar structures such as polar jets, equatorial disks and rotationally-flattened photospheres of Be stars. Such constraints allows us to better estimate the stellar fundamental parameters and refine the mechanisms such as mass loss, pulsation and magnetism that govern the variability and evolution of these stars. In this paper we present a chromatic semi-analytical model of fast rotators, which allows us to study the dynamics and the interaction between the photosphere and the wind of fast rotating stars of O, B, A and F spectral types. Our simple analytical model addresses the oblateness, inclination and position angle of the rotation axis of the star. It produces iso-velocity maps and intensity maps. It includes line profiles, limb-darkening and the von Zeipel effect and the non-radial pulsations. SCIROCCO+ : S imulation C ode of I nterferometric-observations for RO tators and C irC umstellar O bjects including Non-Radial Pulsations, includes all the parameters cited above in order to be fast, powerful and light simulation tool in high angular resolution of rotating objects.